Yesterday, colleagues and I gave a revised version of a course for statisticians, which we've been working on now for about a year. It's called "Futility Analysis". At what point, when data are accruing, can it be established that the chances of further evidence changing one's mind about some hypothesis or other are minimal?

During the day, the boss emailed: would I be able to write something for the blog about the Lib Dem conference? "Futility" and "Lib Dems" … no. Stop it.

That's unfair to the Lib Dems, because what I'd like to write is independent of whichever party is currently conferring. I was quite busy yesterday, as I say, and couldn't write until just now (07:06 on Tuesday morning, welcome back to South Mymms services, yes it is getting colder, isn't it?)

Here's what the conference looked like, to someone with an above-average interest in politics, who glanced at the newspaper websites at lunchtime, kept an eye on Twitter, but who doesn't watch Newsnight or any of that stuff. This is what a day of full-on politics left impinged in my memory:

(*) Vince Cable is miserable.
(*) Nick Clegg doesn't get any longer to speak than any other delegate.
(*) Some Tory said something stupid about Sarah Teather.
(*) A Lib Dem minister, one of the sensible ones, said that niqab bans should be allowed to stand.

Of course, I could learn more about any of these topics, should I choose. But I've deliberately not downloaded today's Telegraph before writing, to see what a "normal" working voter might recall. For all the difference that party conferences have on people who don't follow the news on a 24 hour rolling ticker, they may as well pre-record them and show the same footage for three years at a time.

Not that Vince Cable's gloom doesn't interest me: but it's not news, is it? It interests me in the way that stories about the new Royal Baby interest me: one's glad that he's there, and that's fine, but I can do without the daily updates or commemorative tea towels.

Even the niqab and whether they should be banned … at first I thought I'd offer you a piece about that. But I can't find anything new to say since I last wrote about it, in 2010. Then, as now, a What Not To Wear law would be ludicrous. Ludicrous – offensive – too, however, is the notion that one has the right to wear what one wishes in any situation, without suffering negative consequence. No child of mine would be registered in a school which permitted them to be worn; but it's for the school to decide, not a cabinet minister. No court should tolerate them; but that's for judges to insist upon, not the DPP. We need institutions with more backbone, not yet another bloody law.

No, there's only one thing you can write about the Lib Dems, and their conference doesn't alter it: they are an alliance of centre-Left social democrats and "classic" Liberals. The former would be happier in a Labour government, the latter with Conservatives. Thus the tension in their movement. This tension will be resolved not by a week in Glasgow, but only by the brutal determinant of a general election vote and by the post-election scrabble for power. Induced from evidence, in other words, not deduced from theory.

Which leaves the "Who's up this week?" blather; about as interesting as the current storyline of a soap opera. Party conferences are as much a hangover of the 1950s as the mass membership organisational structures they once served. The mass memberships are gone, the conferences drear on: why?

To set the debate, of course! is the usual rejoinder. Parties hope that eloquent speeches will impress the commentariat and thus set the tone for the next year of trench parliamentary warfare.

Really? Suppose, just for a moment, that in Brighton next week (the single good decision made by Labour in recent years is to hold their conference there) Ed Miliband gives a speech of dizzying oratorical power. That the BBC leads on it for the following 48 hours. "Speech of his life …" "Buys more time to deliver … " "Friends of Mr Miliband say … ". Do you believe such a speech would change the outcome of the 2015 election?

I don't, which is why I'm happy to leave the political class at their conferences this year, why I can't be bothered to drag myself up to Manchester to hang around at the Annual Conservative Gathering For Lobbyists. With apologies to the good people who think differently, my analysis is that the party conference season is totally, utterly futile.